Former New Jersey governor Chris Christie, in his debut as an ABC News contributor on Tuesday’s Good Morning America, said that President Donald Trump has no obligation yet to sit down with special counsel Robert Mueller to answer questions about possible collusion between Trump’s 2016 presidential campaign team and Russia.

“Robert Mueller is not someone to be trifled with…,” said Christie, who also has served as a U.S. Attorney and was a part of Trump’s transition team. “I don’t think the president of the United States, unless there are credible allegations — which I don’t believe there are — should be sitting across from a special counsel.”

As for confronting a sitting POTUS about possible obstruction of justice charges, Christie said that requires a “very high standard,” and “I don’t think we’ve met that high standard yet as to President Trump, but we’ve got to continue to watch it.”